Pharmaceutical capsules from improved thermogelling methyl cellulose ethers
First Claim
1. A thermal gelling methyl cellulose ether composition suitable for use in preparing pharmaceutical capsules by an aqueous dip coating process using preheated pins and having a methoxyl DS of about 1.5-2.0, a C2 -C3 hydroxyalkyl MS of about 0.1-0.4, a 2 wt. % aqueous solution viscosity of about 2-10 cps at 20°
- C and a thermal gel point of about 50°
-80°
C, and a 15-30 wt. % aqueous solution viscosity of about 1,000-10,000 cps at 20°
C, said composition being further characterized by having as a 15- 30 wt. % aqueous solution;
A. essentially Newtonian fluid properties as defined by a power law coefficient, n, of 0.9-1.0 at shear rates of between 0.1-10 sec-1, andB. a 50 sec gel yield strength of at least 150 dynes/cm2 at 65°
C.
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Abstract
Improved thermogelling methyl cellulose ether compositions for use in preparing pharmaceutical capsules by the pin dip coating process are prepared by blending the properties of water soluble methyl and C2 -C3 hydroxyalkyl cellulose ethers to achieve an essentially Newtonian dip coating solution and a rapid high thermal gel yield strength. These properties require a cellulose ether with a relatively narrow molecular weight distribution. Blends of low viscosity methyl cellulose and hydroxypropylmethyl cellulose provide particularly suitable dip solution properties, gel yield strength, and capsule dissolution rates.
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10 Claims
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1. A thermal gelling methyl cellulose ether composition suitable for use in preparing pharmaceutical capsules by an aqueous dip coating process using preheated pins and having a methoxyl DS of about 1.5-2.0, a C2 -C3 hydroxyalkyl MS of about 0.1-0.4, a 2 wt. % aqueous solution viscosity of about 2-10 cps at 20°
- C and a thermal gel point of about 50°
-80°
C, and a 15-30 wt. % aqueous solution viscosity of about 1,000-10,000 cps at 20°
C, said composition being further characterized by having as a 15- 30 wt. % aqueous solution;A. essentially Newtonian fluid properties as defined by a power law coefficient, n, of 0.9-1.0 at shear rates of between 0.1-10 sec-1, and B. a 50 sec gel yield strength of at least 150 dynes/cm2 at 65°
C. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- C and a thermal gel point of about 50°
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8. In a process for preparing pharmaceutical capsules by an aqueous dip coating process using preheated pins and an aqueous bath containing about 15-30 wt. % of a thermal gelling methyl cellulose ether composition having a methoxyl DS of about 1.5-2.0, a C2 -C3 hydroxyalkoxyl MS of about 0.1-0.4, a 2 wt. % aqueous solution viscosity of about 2-10 cps at 20°
- C and thermal gel point of about 50°
-80°
C, and a 15-30 wt. % aqueous solution viscosity of about 1,000-10,000 cps at 20°
C, the improvement comprising using a methyl cellulose ether composition further characterized by having as a 15-30 wt. % aqueous solution;A. essentially Newtonian fluid properties as defined by a power law coefficient, n, of 0.9-1.0 at shear rates of between 0.1-10 sec-1, and B. a 50 sec gel yield strength of at least 150 dynes/cm2 at 65°
C,as the shell forming component of the aqueous dip coating bath. - View Dependent Claims (9, 10)
- C and thermal gel point of about 50°
Specification